parisc: update parisc for new irq_desc

Impact: cleanup, update to new cpumask API

Irq_desc.affinity and irq_desc.pending_mask are now cpumask_var_t's
so access to them should be using the new cpumask API.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>